package DBLayer;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;

/**
 * @Author Kis Boisen Hansen
 * @Version 2006.10.02 - revised marts 2009 FEN
 * @version 2010.10.07 - new connection 
 * @version 2011.11.02 - new methods to handle transaction
 * This class is used to create the connection to the database
 * It is implementet as a singelton. The constructor is private to encure that only
 * one object of the class is generated
 * Version for Sql Server or MySql lines in comments
 */

public class DBConnection
{
	private static final String driver = "jdbc:sqlserver://balder.ucn.dk:1433";
 	private static final String databaseName = ";databaseName=DM76_5";
    private static String userName = ";user=DM76_5";
    private static String password = ";password=MaaGodt";

    private DatabaseMetaData dma;
    private static Connection con;
    private static DBConnection  instance = null;

    private DBConnection()
    {
    	String url = driver + databaseName + userName + password;
        try{
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
            System.out.println("Load of class ok");
        }
        catch(Exception e){
            System.out.println("Can not find the driver");
            System.out.println(e.getMessage());
        }
        try{
            con = DriverManager.getConnection(url);
            con.setAutoCommit(true);
            dma = con.getMetaData();
            System.out.println("Connection to " + dma.getURL());
            System.out.println("Driver " + dma.getDriverName());
            System.out.println("Database product name " + dma.getDatabaseProductName());
        }
        catch(Exception e){
            System.out.println("Problems with the connection to the database");
            System.out.println(e.getMessage());
            System.out.println(url);
        }
    }
    
    public static void closeConnection()
    {
       	try{
            con.close();
            System.out.println("The connection is closed");
        }
       	catch (Exception e){
            System.out.println("Error trying to close the database " +  e.getMessage());
        }
    }
		
    public  Connection getDBcon()
    {
       return con;
    }
    public static DBConnection getInstance()
    {
        if (instance == null)
        {
          instance = new DBConnection();
        }
        return instance;
    }
    
    public static void startTransaction()
    { try{
        con.setAutoCommit(false);
        }
      catch(Exception e){
        System.out.println("fejl start transaction");
        System.out.println(e.getMessage());
      }
    }
    
    public static void commitTransaction()
    { try{
        con.setAutoCommit(true);
        }
      catch(Exception e){
        System.out.println("fejl commit transaction");
        System.out.println(e.getMessage());
      }
    }
    
    public static void rollbackTransaction()
    { try{
        con.rollback();
        con.setAutoCommit(true);
        }
      catch(Exception e){
        System.out.println("fejl rollback transaction");
        System.out.println(e.getMessage());
      }
    }
}
